238 NEWMAN ON THE 



will be observed that each of the remaining groups, in some of 

 their genera, copy, as it were, the quantity of surface and power, 

 as well as reticulation of wing, possessed by the Libellulina. The 

 differences in the development of the pro- meso- and metathorax, 

 afford us steady assistance in the distribution of the circumferen- 

 tial groups. The Ephemerina possess the minimum degree of 

 prothorax and metathorax. The reverse is the character of the 

 Perlina; in these we find the prothorax and metathorax of 

 considerable volume, though not the maximum degree, and the 

 raesothorax proportionally decreased. 



The Ephemerina and Perlina are thus placed in exact oppo- 

 sition to each other. From Ephemera we perceive very slight 

 difference in structure, if we pass to Nemopteryx, thence to 

 Panorpa, and thence to Bittacus ; and the minute Boreus is too 

 closely related to Panorpa to be excluded. These four genera 

 constitute the Stirps Panorpina. The hind wings in this group 

 equal or exceed the fore wings in size- From the Panorpina 

 we pass to another group, distinguished by a still greater de- 

 velopment of prothorax and metathorax, a less development of 

 mesothorax, a greater perfection of mouth, and a decided 

 necromorphous metamorphosis. This group includes the 

 Myrmeleonina and Corydalina of Mr. MacLeay. The larva? 

 are among the most singular productions of nature. They are 

 exceeding voracious, subsisting on the juices of other insects 

 which they kill : they conceal themselves on leaves, under 

 rubbish, or construct pitfalls in the earth. They have mandi- 

 bles perforated at the extremities, through which they suck the 

 juices of their victims. Raphidia seems, in some degree, a 

 departure from the typical character of this group, its larvae, 

 according to Mr. Waterhouse, feeding on the bark of trees. On 

 this subject I cannot speak from observation ; but, if the 

 description is correct, it is a singular proof of the waywardness 

 of nature, which seems to defy our arbitrary laws. Sialis has 

 a quiescent pupa. Thence we pass to Perla, or rather the 

 Perlina : here the metamorphosis is strictly isomorphous ; 

 the mouth strictly mandibulate, the pro- and metathorax fully 

 developed, and the mesothorax restricted. From the Perlina 

 we proceed to Embia, thence to Termes, and from Termes to 

 Psocus. The Genus Embia exists without a history; its 

 general habit points to Termes, as the type of its economy, but 

 at this we can only guess. The connexion between Psocus 



